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Linux

Fix serial port permission denied errors on Linux

April 8, 2013 Linux Jesin A 29 Comments

linux category thumbnail

The ancient serial port which is no longer found on the latest motherboards and even the not so latest laptops is still used for connecting to the console of networking devices, headless computers and a lot other applications. On computers which do not have built-in serial ports USB-to-Serial adapters can be used. Linux identifies inbuilt serial ports as /dev/ttyS0, /dev/ttyS1,….. /dev/ttySn and USB-to-Serial adapters as /dev/ttyUSB0, …. /dev/ttyUSBn and they can be accessed using terminal emulator applications like PuTTY, minicom and screen.Continue Reading…

Tags: linux, linux commands, putty, serial

How to manage jobs in Linux – fg bg kill Ctrl+Z

July 2, 2012 Linux Jesin A 1 Comment

linux category thumbnail

How many times did you start something which is time consuming and waited for it to end until you could use the console again. We have all faced a situtation when we just stare at the screen for a process to get over after we have initiated it. It could be something as simple as copying a large file from a removable media or installing packages using yum/apt-get from online repositories over a slow internet connection (ouch!). Once started you will not get back the command shell until the process is done, so what do you do ? Hit Ctrl+C terminate it and hope to do it over the weekend ? Take a coffee break ? Count the number of keys on the keyboard ? Why not press Ctrl+Z and get the work done in background while you use the console to do something else. In this article I will cover how to suspend a process a.k.a. job, run it in the background, bring it to the foreground, terminate it if necessary.Continue Reading…

Tags: linux, linux commands

How to configure a Linux PPTP VPN client

November 27, 2011 Linux Jesin A 13 Comments

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Configuring a VPN client connection is a simple matter of point and click in Windows OSes, but in Linux it is involves installing a package, configuring passwords, VPN server settings and finally routing the traffic destined for the VPN network via the VPN connection. The package named pptp is used on the client side for configuring a connection. To setup a VPN server read How to setup a VPN Server in Windows Server 2008. This tutorial is for both Debian Linux variants and Red Hat Linux variants.Continue Reading…

Tags: linux, vpn

How to setup an unmanaged Debian server

October 30, 2011 Linux Jesin A 1 Comment

linux category thumbnail

So you’ve bought a shiny new VPS or dedicated unmanaged server to cut costs on hosting but don’t know how to begin ? Read this post to make this easier.  This tutorial will cover the instructions for a basic setup of a Debian unmanaged VPS or dedicated server. The following are covered in this article

  • Configuring the Timezone
  • Selecting locales
  • Creating a sudo user
  • Securing SSH
  • Adding firewall rules

The first task is to update the apt database and check if any installed packages can be upgraded.

apt-get update && apt-get upgrade

Continue Reading…

Tags: debian, linux

How to use MSMTP with Gmail, Yahoo and PHP Mail

October 24, 2011 Linux Jesin A 12 Comments

linux category thumbnail

This is a three in one tutorial which combines how to use MSMTP to send mails via Gmail and Yahoo servers and how to use MSMTP with PHP Mail() function instead of the default sendmail.

Installing msmtp

To install msmtp on Red Hat/CentOS/Fedora type of distributions

yum install msmtp

To install msmtp on Debian/Ubuntu type of distributions

apt-get install msmtp

Configuring msmtp with Gmail and Yahoo

Create or edit the msmtp configuration file in the user’s home directory. I use VI editor to achieve this

vi ~/.msmtprc

Add the following lines to the file, it configures msmtp for both Gmail and Yahoo

account yahoo
tls on
tls_starttls off
auth on
host smtp.mail.yahoo.com
user user1
from user1@yahoo.com
password ******
account gmail
tls on
auth on
host smtp.gmail.com
port 587
user user1@gmail.com
from user1@gmail.com
password ******

Since the file contains sensitive data like passwords you should assign secure permissions

chmod 600 ~/.msmtprc

Continue Reading…

Tags: linux, php, php.ini

How to save IPtables rules in Debian

October 22, 2011 Linux Jesin A 5 Comments

This article explains how to make IPtables firewall rules sustain a boot in Debian. But this can also be applied on other Debian based OSes like Ubuntu and Knoppix. You show execute all these commands as the root user or use the sudo command to do it.

First view the list of rules in IPtables

iptables -L

If its a new installation there will be no rules. So add some firewall rules, the following rules will allow HTTP, HTTPS, FTP, SMTP, SSH incoming connections and rejects all other incoming connections including ICMP ping packets.Continue Reading…

Tags: iptables, linux, linux system files

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